Technical "Follow" and "Unknown Member" issue

(I'm not going to use the template, since I'm not sure how should I report this using that same template; if I do need to use the template though, please tell me and I shall edit this)

So here's the thing: apparently I can follow people on the forum without any problems, but they can't follow me. Aerilia told me that, when I liked one of their posts in my profile page, it shows as a like made by a (deleted member). Also, under "Conversation Participants", instead of showing my name on it, it shows as " Unknown Member". I can't even reply to the convo too, apparently.

Here's a screenshot of my convo with Aerilia. You can also see how I'm identified as "Unknown Member":

And here's another screenshot of what happens everytime I try to reply in a convo:

I'd appreciate if any of you could give it a look please. Nothing too urgent though, since I can do pretty much everything else normally.

(I figured this would be a lot simpler and easier to explain without using the template but if you need me to I'll edit this)

So basically any time that I try to follow Marcus Antonius on here it always says "Server error" and doesn't let me follow. I tried reloading the page and logging out and logging back in, and it didn't work. I don't know if that's something fixable, and I know it's not urgent or anything, it's just slightly annoying but no rush or anything to figure it out.